Often, components having surfaces in need of machining are configured such that the surface is hard to reach. Thus machining these surfaces to prolong the life of the component is difficult. One such component having surfaces that need to be machined are valves typically found on submarines, ships and the like, which are welded inline with piping. These valves have seat surfaces that corrode or wear while in service. These seats have to be re-machined and built up with shims to restore the sealing surface.
The current repair method involves using a portable right angle machine tool that is mounted to the cover flange of the valve with a rotating cutter axially aligned with the seat. The cutter has a small fixed thread feed screw that is activated by a star wheel with a trip arm so that a cutter mounted on a cutter head incrementally moves radially as the cutter head is rotated. The feed rate cannot not be varied by the operator, as the star wheel geometry and lead screw pitch are fixed. Such incremental advancement does not allow for variably controlling the radial advancement of the cutter, which may be beneficial for surfacing operations.
The current repair equipment has the rotating cutter driven by a gear train comprising of multiple idler gears. This arrangement is heavy and bulky, especially on machines for servicing larger valves.
After the cutter reaches its maximum radial travel, the star wheel must be manually rotated in the opposite direction to return the cutter to its starting point for a second cut. This is typically accomplished by using a small rod threaded through a hole in the mounting plate and slowly manipulating the star wheel in the reverse direction. This time-consuming retraction effort can have a significant impact on the efficiency of the machining process.